Steel bar bending apparatus is commonly used in a construction site for bending steel bars in constructing a structure or a building. The general structure of the common steel bar bending apparatus comprises a fixed roller and a movable roller to provide a rolling contact with a steel bar to be bent and a fulcrum block adjacent the fixed roller, but having a space therebetween to allow the steel bar to extend therethrough. The movable roller is driven to bend one end of the steel bar about and fulcrum block, while the fixed roller serves to hold the opposite end of the steel bar. The movement of the movable roller is substantially circular with the center at the fulcrum block.
An early day steel bar bending apparatus may only perform bending operation of a predetermined angle and no adjustment of the bending angle is readily available. A later developed steel bending apparatus overcomes such a problem and allows a multiple angle bending operation. However, there is still a limitation on the number of the angles that may be achieved by the apparatus.
Furthermore, conventionally, the steel bar bending apparatus that provides a multiple angle adjustment is usually controlled by an IC-based controller which may easily malfunction, due to the severe environment of a construction site, causing incorrect angle of bending.
To overcome such a problem, a steel bar bending apparatus which comprises several bending units combined together to provide a multiple angle adjustment was taught. Such an apparatus, although being controlled in a mechanical way rather than an IC-based fashion, requires a large installation space and the combination of the bending units is quite time-consuming and difficult. In addition, the design of such an apparatus is an open style, in which the transmission and control elements, such as gear, worm, worm gear, are exposed to the severe environment of the construction site so that corrosion and aging problem may quick raise and thus causing imprecision of angle in bending a steel bar.
Such a steel bar bending apparatus also have other drawbacks, for example (1) it does not allow an arbitrary addition of bending units in forming different angle bends on the same steel bar, (2) the open style design makes it lack of an aesthetic appearance and (3) it has a poor fine adjustment of the bending angle.
Thus, it is desired to have an improved bending device to be incorporated in a steel bar bending apparatus which allows simple and ready combination of an arbitrary number of bending units to perform a multiple bending angle settings in an efficient and precision manner to as to substantially overcome the problems and drawbacks encountered in the prior art designs.